The present invention relates to a coin sorting device which is suitable for vending machines.
For this type of conventional coin sorting device, an electronic coin sorting system has been generally adopted. The electronic coin sorting system is equipped with a coin sensor in a coin passage through which deposited coins pass. The coin sensor consists of an exciting coil to which a signal of given frequency is input from an oscillation circuit, and a reception coil arranged as electromagnetically coupled with the exciting coil. When there is no coin in the coin passage, the coin sensor generates a constant induced electromotive force of given frequency. The presence of a coin in the coin passage results in eddy currents developing in the coin and the induced electromotive force obtained by the reception coil shows a characteristic change unique to the coin. A voltage change, for example, is used as a parameter for extracting the characteristic change, thus determining the denomination and genuineness of the coin.
The following is a detailed explanation about this determination. In case where data obtained by the reception coil are voltage data upon which the determination is made, the maixmum and minimum values of voltage are preset such that the coin is determined as a true coin when the maximum and minimum voltage values are within the preset range, and as a forged or false coin when it is beyond the range. It should be noted that a plurality of coin sensors are provided for different characteristics of a coin, such as diameter, material, and thickness, assigning each sensor a frequency adaptable to each sensor's screening.
The truth/falsity determination of a coin is thus made, but forged or false coins may be frequently deposited to a vending machine depending on the site the vending machine is located. In expectation of such a case, the coin sorting device is provided with a changeover switch for changing over degrees of sorting precision so that the sorting can be improved.
However, since the conventional coin sorting device is to improve the sorting precision by changing the preset maximum and minimum values, a change in range do not always bring proper values for all the false coins. Therefore, even if the sorting precision is improved, a problem remains in that some false coins falling in the same data range as that for true coins cannot be eliminated.
Furthermore, the change in range generally stiffens the requirements for all the ranges of identifying characteristics such as diameter, material, and thickness across the board, and this reduces the rate of acceptance of true coins.